Active Matrix Organic Light Emitting Diode (AMOLED) displays have been highly anticipated by electronic consumers due to their well-recognized advantages in power consumption, pixel brightness, viewing angle, response time, and contrast ratio over liquid crystal displays (LCD). (See, e.g., G. Gu and S. R. Forrest, IEEE Journal of Selected Topics in Quantum Electronics, vol. 4, pp. 83-99, 1998, the disclosure of which is incorporated herein by reference.) However, the advances promised by AMOLEDs have not been realized at least partially as the result of limitations in conventional active matrix thin-film transistor (TFT) backplanes. The current active matrix TFT backplanes used to drive AM-LCD pixels are typically made of amorphous silicon (a-Si), which has a low mobility (−1 cm2V−1s−1) and poor stability, and is therefore unsuitable for AMOLED pixels. (See, M. J. Powell, IEEE Transactions on Electron Devices, vol. 36, pp. 2753-2763, 1989, the disclosure of which is incorporated herein by reference.) As a result of these deficiencies, currently AMOELD displays are driven by low temperature polycrystalline silicon (poly-Si) TFTs that suffer from high fabrication cost and time, and device size, orientation, and inhomogeneity limitations, all of which present a severe challenge to increasing display size and production yield. (See, e.g., C.-P. Chang and Y.-C. S. Wu, IEEE electron device letters, vol. 30, pp. 130-132, 2009; Y.-J. Park, M.-H. Jung, S.-H. Park and O. Kim, Japanese Journal of Applied Physics, vol. 49, pp. 03CD01, 2010; and P.-S. Lin, and T.-S. Li, IEEE electron device letters, vol. 15, pp. 138-139, 1994, each of the disclosures of which are incorporated herein by reference.)
Solution processible organic semiconductor materials are attractive alternatives to poly-Si because of their homogeneity, low cost, and varied deposition methods. (See, e.g., D. J. Gundlach, et al., IEEE Electron Device Letters, vol. 18, pp. 87-89, 1997; H. Yan, et al., Nature, vol. 457, pp. 679-686, 2009; and A. L. Briseno, et al., Nature, vol. 444, pp. 913-917, 2006, the disclosures of each of which are incorporated herein by reference.) However, in a conventional TFT architecture, the low-mobility of organic films requires a large source-drain voltage (>20 V) to turn on the OLED devices. (See, H. Sirringhaus, et al., Science, vol. 280, pp. 1741-1744, 1998, the disclosure of which is incorporated herein by reference.) Stable high-transconductance organic thin-film electrochemical transistors using a high capacitance electrolyte as the gate dielectric layer have been demonstrated. (See, e.g., J. H. Cho et al., Nature Materials, vol. 7, pp. 900-906, 2008; and Y. Xia, et al., Advanced Functional Materials, vol. 20, pp. 587-594, 2010, the disclosures of each of which are incorporated herein by reference.) Using these devices it is possible to control a high efficiency red, green and blue AMOLED with supply voltages near 4 V and sub-1 V driving voltages. (See, e.g., D. Braga, et al., Advanced Functional Materials, vol. 22, pp. 1623-1631, 2012, the disclosure of which is incorporated herein by reference.) In addition, carbon nanotube enabled vertical organic thin-film field effect transistors that give on-currents sufficient to drive OLED pixels at low operating voltages because of their intrinsic short channel lengths have also been demonstrated. (See, e.g., M. A. McCarthy, et al., Science, vol. 332, pp. 570-573, 2011, the disclosure of which is incorporated herein by reference.) Though these approaches are promising, the required fabrication steps still limit the simplicity of system architecture and consequently production costs.